There were a number of positives for Arsenal yesterday, as there must be to get a result against a team the caliber of Bayern Munich, but none bigger than the performance of Arsenal's (figurative) No. 1, Petr Čech.
The narrative of Arsenal's Champions League campaign prior to yesterday's win was fixated on the goalkeeper in the first two matches: David Ospina. Ospina's shoulder injury made Wenger's choice for him, and allowed us all to circumvent the debate over who should start and why. Suffice it to say, yesterday was a 180 degree shift from the first two matches, largely in part due to the Czech's calm, assured performance.
While it is arguable Čech did not make any individual world class saves (his fingertip save against Robert Lewandowski was underrated, methinks), he put in a world class performance between the sticks yesterday. He made every save he needed to, his saves were cleared from immediate danger, and he exuded confidence in the face of nearly continuous Bayern Munich possession and pressure. While hard to quantify, his ability and confidence permeated to the Arsenal back four, who also performed excellently.
His performance was everything Arsenal fans hoped for when he joined the club from Chelsea in the summer. Long may his reign as Arsenal's No. 1 in the Champions League continue.